Spikes and DBT's
Nichevo13
mats have any appreciable effect on sound??? I tend to be cynical about
cables since I cannot hear any difference, I have had the same experience
with spikes... Is my hearing just poor???
AudioEnz
Spiking speakers to the floor does, in my experience, improve the sound of a
speaker. Spiking can clear up the midrange and tighten up the bass.
Or are you speaking of cones and the like under audio electronics?
Michael Jones
Editor, AudioEnz
--------------------
New Zealand's online hi-fi and home theatre resource
http://www.audioenz.co.nz
Nousaine
I conducted a careful blind test of speaker stands (published in Stereo Review
in 1994) where a lead-filled stand with both the feet and the speaker pad
spiked was compared to a stamped steel stand duct taped to an empty cardboard
12-inch speaker carton and height matched with paperback books.
I used 4 identical speakers with sequential serial numbers which were verifed
tobe within 0.5 dB of each other in the room used for the test. Speakes were
randomly assigned postions and then rotated through all possible positional
assignments. The stands were hidden with a blck cloth and 6 listeners were used
in multiple sessions.
The results? People had a definite speaker position preference but the stand
used to get to that position wasn't important. meaning your hearing is not a
reason that you can't "hear" stands :)
Thomas A
If there is a difference, it would depend greatly on the type of
speaker and the type of floor. There have been several blind test
made by the Swedish Audio Technical Society, comparing spikes vs very
soft feet. They were positive. It has not been published peer
reviewed though. One test involved a mechnical lift that lifted the
speaker 3-4 mm off and on hard and soft feet. It is possible that the
lift of 3 mm casued the difference. The other thing, it may be
possible to feel different vibrations in the floor if the speaker is
coupled to a wood floor than when it is isolated. I've measured that
there may be an about 0.5-1 dB higher level of a 125 Hz test tone
when the speaker is spiked to a wooden floor compared to when it is
isolated. This is the range where my wooden floor also vibrates quite
much.
Thomas
Howard Ferstler
To my knowledge, nobody has done any decently scientific comparisons
proving that spikes do anything to improve the sound of speakers. One
reviewer did do a comparison of speakers on heavy stands vs sitting
them on cheap, borderline flexible stands and there were no results
that showed the super stands to be sonically superior.
Of course, doing any comparisons of that kind with two pairs of
speakers is tricky, since the different locations of each of the two
pairs will also make each pair sound different from the other, and if
you want to put the systems in exactly the same place and simply
switch from no spikes to spikes, the time delay between listening
sessions will come close to invalidating any conclusions.
I say that all you need on hard floors are some good, standard rubber
feet. On carpet, you actually do not need anything at all - not even
feet. Just put the flat bottom of the speaker on the rug and be done
with it.
Spikes, of course, can do one thing, assuming they are adjustable
versions. They can help you to get a tall tower speaker better aligned
to a true vertical position (for a better appearance), and I suppose
once they sink into a carpet they will make a skinny tower a bit more
difficult to push over. Not a bad thing if the enthusiast has small
children.
Howard Ferstler
Webmarketing
height. I have heard the affects of isolators, though, on low frequencies.
Unlike spikes which are intended to "couple" the stand to the floor,
isolators (usually vinyl or rubber) tend to isolate them from the floor.
The use of isolators tends to cause less sympathetic resonance at low
frequencies and the bass sounds a little "tighter." woofers and subwoofers
are usually pretty good at causing sypathetic vibrations from objects around
them. How much the effect would be would depend a lot on the room itself.
It may be meaningless or fairly important depending on the character of the
room and things in it. My powered subwoofer changes the character of its
sound quite audibly with the use of sorbothane isolators. I think just
getting it up off the floor makes the major difference.
Fred
AudioNow!
http://www.audionow.com
"Nousaine" <nous...@aol.com> wrote in message
news:a8a4kl$9im$1...@bourbaki.localdomain...
Nousaine
>I've never "heard" stands either as long as the tweeters were at the same
>height. I have heard the affects of isolators, though, on low frequencies.
>Unlike spikes which are intended to "couple" the stand to the floor,
>isolators (usually vinyl or rubber) tend to isolate them from the floor.
>The use of isolators tends to cause less sympathetic resonance at low
>frequencies and the bass sounds a little "tighter." woofers and subwoofers
>are usually pretty good at causing sypathetic vibrations from objects around
>them. How much the effect would be would depend a lot on the room itself.
>It may be meaningless or fairly important depending on the character of the
>room and things in it. My powered subwoofer changes the character of its
>sound quite audibly with the use of sorbothane isolators. I think just
>getting it up off the floor makes the major difference.
>
>Fred
>AudioNow!
>http://www.audionow.com
As I said speaker position is an important factor but usually an inch doesn't
make that much of a difference unless the speaker in question has a radically
poor radiation pattern.
I've never seen the need for isolators either although I suppose they might be
useful in certain circumstances. I've always found buzzing objects to be more
easily dealt with at the source of the buzz or makin a small adjustment to the
cone/port direction.
Thomas A
Whether it is audible or not, I cannot say for myself. But it cannot
hurt to isolate the speaker from a flexing wood floor. Depending on
the amplitude of vibration, "phase/frequency difference" between the
front and back at the floor where the speaker feet sits (could be
different if the weight of the front of the speaker is more heavy than
the back and by local differences in the wood floor), and the height
of the speaker. Assuming a movment downwards of 0.1 mm at front feet
and simultaneosly 0.1 mm up at back would imply a 0.2 mm difference.
If the speaker height is 120 and its depth is 40 cm, the top of the
speaker would move forward about 0.6 mm.
There would also be a resonance peak of the floor/speaker interface
and when forces are generated at this resonance, the speaker cabinet
would move more.
But this is all theory. I have no idea what the real numbers would be.
http://www.mosaic.fi/markku/sweeptest.html
Thomas
Nousaine
Lots of assumptions here. To get "movement" you have to remember that the
acoustical output of the cone/port or enough energy transmitted through the
feet are going to have to generate enough force to move a subwoofer cabinet.
When these devices run 40+ pounds I'm guessing that cabinets themselves are
seldom if ever 'moved'
Decouplers also assume that the transmission of energy is being primarily
transmitted through the feet on the cabinet to the floor or surrounding
objects. IME any buzz/rattles I get from subwoofers are often transmitted
acoustically and can be controlled at the buzz source. I've never found a
buzzing picture to be quelled by using isolators but often you can squelch one
by moving the cone away from a certain wall or putting a pad on the picture
frame.
>There would also be a resonance peak of the floor/speaker interface
>and when forces are generated at this resonance, the speaker cabinet
>would move more.
>
>But this is all theory. I have no idea what the real numbers would be.
>
>http://www.mosaic.fi/markku/sweeptest.html
>
>Thomas
As I've said I haven't found isolators to be especially useful at subwoofer
frequencies. My personal system uses eight fifteen inch long stroke woofers
mounted in an infinite baffle that has no hard attachments to building
structure (all adjacent surfaces are glued with non-drying resilient adhesive)
but I still get significant structure borne energy transfer in addition to the
acoustically transmitted stuff with high power low frequency programs. With the
right program material it adds greatly to realism.
With other program, such as organ recordings ro acoustic bass, where there is
not enough energy in the recording to produce structure borne information
things sound just right.
If you are going to try isolators I'd recommend my old favorite. A plastic bag
with a sponge soaked with a heavy weight oil with weight dispersing plates and
a really tightly sealed metal or plastic pan on the bottom.
Arny Krueger
> If you are going to try isolators I'd recommend my old favorite. A plastic bag
> with a sponge soaked with a heavy weight oil with weight dispersing plates and
> a really tightly sealed metal or plastic pan on the bottom.
Recall that we saw another approach implemented a few Saturdays ago.
The speakers were suspended from the ceiling with 4 lengths of nylon
twine. It was claimed by the owner (who has a PhD in engineering with
considerable training and experience with noise and vibration) that
this nylon twine suspension did a good job of isolating vibrations.
So much so that the ceiling panels were similarly individually
suspended.
Thomas A
> thomas_...@hotmail.com (Thomas A) wrote:
[quoted text deleted -- deb]
> >Whether it is audible or not, I cannot say for myself. But it cannot
> >hurt to isolate the speaker from a flexing wood floor. Depending on
> >the amplitude of vibration, "phase/frequency difference" between the
> >front and back at the floor where the speaker feet sits (could be
> >different if the weight of the front of the speaker is more heavy than
> >the back and by local differences in the wood floor), and the height
> >of the speaker. Assuming a movment downwards of 0.1 mm at front feet
> >and simultaneosly 0.1 mm up at back would imply a 0.2 mm difference.
> >If the speaker height is 120 and its depth is 40 cm, the top of the
> >speaker would move forward about 0.6 mm.
>
> Lots of assumptions here. To get "movement" you have to remember that the
> acoustical output of the cone/port or enough energy transmitted through the
> feet are going to have to generate enough force to move a subwoofer cabinet.
> When these devices run 40+ pounds I'm guessing that cabinets themselves are
> seldom if ever 'moved'
If you look at the link, there is a quite large difference between
coupling and decoupling, and the effects of standing waves in the room
acting on the wood floor and in turn the speaker. As I mentioned
below, the movement is different depending on speakers as heavy
cabinet tend to give higher local pressure pressure and reduce
frequency and Q of the floor vibration. Whether the vibrations are
capable of moving the speaker significantly to be audible, I cannot
say, but there is a clear difference.
>
> Decouplers also assume that the transmission of energy is being primarily
> transmitted through the feet on the cabinet to the floor or surrounding
> objects. IME any buzz/rattles I get from subwoofers are often transmitted
> acoustically and can be controlled at the buzz source. I've never found a
> buzzing picture to be quelled by using isolators but often you can squelch one
> by moving the cone away from a certain wall or putting a pad on the picture
> frame.
The floor flex from energy transmitted from acoustical energy which in
turn affects the speaker and other objects. The optimal goal is to
have the speaker standing as still as possible. See previous link. It
however, also isolates transmission of vibrations from speaker to the
floor, which could act as a second speaker with its very large surface
area. See
http://www.sonicdesign.se/sdfeet.html
>
> >There would also be a resonance peak of the floor/speaker interface
> >and when forces are generated at this resonance, the speaker cabinet
> >would move more.
> >
> >But this is all theory. I have no idea what the real numbers would be.
> >
> >http://www.mosaic.fi/markku/sweeptest.html
> >
> >Thomas
>
> As I've said I haven't found isolators to be especially useful at subwoofer
> frequencies. My personal system uses eight fifteen inch long stroke woofers
> mounted in an infinite baffle that has no hard attachments to building
> structure (all adjacent surfaces are glued with non-drying resilient adhesive)
> but I still get significant structure borne energy transfer in addition to the
> acoustically transmitted stuff with high power low frequency programs. With the
> right program material it adds greatly to realism.
>
> With other program, such as organ recordings ro acoustic bass, where there is
> not enough energy in the recording to produce structure borne information
> things sound just right.
>
> If you are going to try isolators I'd recommend my old favorite. A plastic bag
> with a sponge soaked with a heavy weight oil with weight dispersing plates and
> a really tightly sealed metal or plastic pan on the bottom.
I already use the Sonic design isolators. They have a defined
resonance below 7 Hz when loaded correctly. My system do not do very
deep in bass (35 Hz) so there is no problem. Another system I've
listened too have 4 x 15 inch woofers and give sound pressures of 145
dB at 17 Hz, and have its -5 dB point at 10 Hz. Still it uses custom
made SD feet and it works fine. Subwoofers with heavy passive
radiators and too light cabinets are however, not very good to
decouple, since the create quite large reaction forces that may cause
speakers to move. Such subs may be better to couple to the floor.
ScottW
wrote:
I have used a similar approach to suspend a TT in an old house
with extremely unstable floors. It isolated the table from
vibration and footfalls extremely well. Unfortunately, the lack
of damping required some patience if it was bumped. We used 60
lb monofilament x ~50 strands. The transluscent cord created
was more aesthetic than twine :).
ScottW
Mark Wilkinson
From: "Thomas A" <thomas_...@hotmail.com>
Another system I've
> listened too have 4 x 15 inch woofers and give sound pressures of 145
> dB at 17 Hz, and have its -5 dB point at 10 Hz.
Wow! I've never heard of numbers like these -- not from anything ---
including live sound boxes. Even available horn loaded designs aren't
within a half a mile of these #'s.
PLEASE describe this setup! Thanks, Mark
Nousaine
much snipped .....
>If you look at the link, there is a quite large difference between
>coupling and decoupling, and the effects of standing waves in the room
>acting on the wood floor and in turn the speaker.
I saw no reference to standing waves on the site.
As I mentioned
>below, the movement is different depending on speakers as heavy
>cabinet tend to give higher local pressure pressure and reduce
>frequency and Q of the floor vibration.
According to the un-defined graphics on the referenced site (no details as to
what/how those pictures were generated) one would have to assume that most of
the energy from the speaker is transmitted through the feet (or spikes in this
case.)
This seems to be contradicted by your later reference where it's said that
speaker location relative to adjacent room surfaces may have a larger effect.
While I have no general use for spikes the site seems to be, for the most part,
promoting a solution looking for a problem.
Whether the vibrations are
>capable of moving the speaker significantly to be audible, I cannot
>say, but there is a clear difference.
>The floor flex from energy transmitted from acoustical energy which in
>turn affects the speaker and other objects. The optimal goal is to
>have the speaker standing as still as possible.
The only speaker I've ever seen that claimed to move was a Sunfire subwoofer
which had such a high moving mass driver and tremendous imbalance where people
have claimed they've made it "walk." However I've not seen this myself and I've
never seen the Sunfire people perform such a demo at the CES.
See previous link. It
>however, also isolates transmission of vibrations from speaker to the
>floor, which could act as a second speaker with its very large surface
>area. See
>
>http://www.sonicdesign.se/sdfeet.html
>
>>
>> >There would also be a resonance peak of the floor/speaker interface
>> >and when forces are generated at this resonance, the speaker cabinet
>> >would move more.
One of your sites suggests that the peak energy is greater and of higher Q with
decoupling.
>http://www.mosaic.fi/markku/sweeptest.html
Interestingly the data on this site tends to show that energy was higher in
amplitude and Q when the decouplers were used. And that the placement of the
speaker and other room artifacts may have had a large effect.
As you said before there would be nothing wrong with isolating the speakers but
the main question is whether one need to bother. I'd say your site references
don't really make a very good case for that.
>I already use the Sonic design isolators. They have a defined
>resonance below 7 Hz when loaded correctly. My system do not do very
>deep in bass (35 Hz) so there is no problem. Another system I've
>listened too have 4 x 15 inch woofers and give sound pressures of 145
>dB at 17 Hz,
Under what conditions?
and have its -5 dB point at 10 Hz. Still it uses custom
>made SD feet and it works fine.
I'd be guessing it would work fine without them as well.
Subwoofers with heavy passive
>radiators and too light cabinets are however, not very good to
>decouple, since the create quite large reaction forces that may cause
>speakers to move. Such subs may be better to couple to the floor.
But doesn't a moving speaker also decouple itself? The movement is dissipating
energy, isn't it?
Webmarketing
were 4 15" Bozak woofers on each side of the stereo pair and they
were mounted in a concrete wall. The backwave went outdoors through
a special flue. This system had more bass than anything I've ever
heard in a cabinet. I don't know what the SPL was at 17hz but
reproducing 17hz wasn't an issue for sure.
Fred
AudioNow!
http://www.audionow.com
"Mark Wilkinson" <wilki...@naxs.net> wrote in message
news:a8fre6$lmt$1...@bourbaki.localdomain...
Mark Wilkinson
Yea, 17hz isn't so surprising ... neither is 145 db ... but 145 db @
17hz????? I've never read of anything that can do that. Mark
Richard D Pierce
Thomas A <thomas_...@hotmail.com> wrote:
>
>Another system I've listened too have 4 x 15 inch woofers and
>give sound pressures of 145 dB at 17 Hz, and have its -5 dB
>point at 10 Hz.
This is, truly, quite an extraordinry claim.
Assuming, for the moment, the sound pressure level claimed is
measured at a conventional 1 meter, 145 dB SPL tells us that the
source is producing 2000 ACOUSTIC WATTS, assuming half-space
radiation.
TWO THOUSAND ACOUSTIC WATTS! That's a TRULY extraordinary claim.
Assuming that speaker had an efficiency of 5% (since you do not
indicate that it is horn loaded), it could ONLY produce such a
sound pressure with an electrical input of 2,000/5% or 40,000
electrical watts.
FORTY THOUSAND ELECTRICAL WATTS! That's another TRULY
extraordinary claim.
Now, you state that this system is comprised of 4 15" woofers.
TO produce a sound pressure level of 145 dB at 17 Hz would
require that the peak excursion of these woofers MUST be AT
LEAST 500mm.
FIVE HUNDRED MILLIMETERS! TWENTY INCH EXCURSION! Now THAT'S a
REALLY TRULY AWESOMELY EXTRAORDINARY CLAIM IF THERE EVER WAS
ONE.
Let's go a couple of steps further. Assuming you DO have 15"
woofers whose excrusion is larger than the diameter of the
woofer (extraordinary!). To achieve a 5% efficiency, assuming
absolutely lossless, maximal efficiency reflex tuning, we'd have
to have a cabinet volume NO LESS THAN 4400 liters.
FOUR THOUSAND, FOUR HUNDRED LITERS FOR CABINET VOLUME! ONE
HUNDRED AND FIFTY THREE CUBIC FEET. NEARLY 6 CUBIC YARDS!
That's a box that's nearly 6 feet by 6 feet by 6 feet!
Sorry, Thomas, if that's what someone told you this system could
do 145 dB at 1 meter at 17 Hz, they were doing a pretty good job
of SERIOUSLY pulling your leg.
Extraordinary!
(Let's assume, instead, 4 15" woofers with an excursion limit
each of, say, 1.5 cm, a little over 1/2", which is VERY
generous. SUch a system would be capable of producing NO MORE
THAN 116 dB SPL at 1 meter before running into excursion
limiting.)
But 145 dB at 17 Hz? Forget it.
--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| DPi...@world.std.com |
Thomas A
Ok sorry to give such a "extrordinary claim". My memory from the
written text was not that good, the actual sound pressure limit was
139 dB, but here I quote the text from Ino speakers company:
"Our largest bass system Profundus Z-4 is the largest sound-pressure
generating system in the world. If it would be compared to a
servo-controlled 10 inch woofer in a closed box, the peak of the
driver would have to be 200 centimeters to compare to the Z-4. A
conventional subwoofer thus only produce less than 1/20,000 of the
sound pressure of Z-4, than can move 75 liters of air peak to peak
close to its lower frequency limit. A maximal sound pressure of 139 dB
can be generated to below 20 Hz.
The 139 dB that Z-4 generates is extremely high and many rooms may
also give 6 dB higher sound pressure because of its walls. World
famous recording engineer Bertil Alving have measured the system in
the studio "Studio Blue" and have confirmed the lowest limit to 14 Hz.
For a test of maximal sound pressure if was measured to 137 dB at 17
to 55 Hz about 7 meters distance from the speakers. At the mixer
tables the sound pressure was 134 dB, which corresponds to a sound
pressure of 145 dB 1 meter from the speakers. On one meter however,
max sound pressure is in normal cases 139 dB in all normal rooms since
the impact of room at such distances is minimal."
So the level was lower than I first wrote, but still very high. If you
want to confirm this, you will have to talk to Bertil Alving who did
the measurements, or speak directly to Ino Audio. If you do not
believe it you have to travel to Sweden to measure it by yourself.
They have also even bigger systems now, the Z-10, consisting of (I
think) 10 subwoofers. That's all I can say.
Thomas
Nousaine
True. I have a system with 8 fifteen inch 23-mm Xmax drivers mounted
in an infinite baffle arrangement which will produce 120 dB at 2
meters over the 12-62 Hz range when powered by a Crown MacroTech 5000
in a real room.
145-dB is indeed forgettable at low frequencies. I would guess that
the poster used an uncalibrated SLM at a not-specified distance to
make the readings ......or more likely just a guess.
Stewart Pinkerton
I guess he means 105dB, although even that would be pretty impressive
at 17Hz! Or of course, he could be describing a pressure-loaded
automobile system................................
--
Stewart Pinkerton | Music is Art - Audio is Engineering
Thomas A
> thomas_...@hotmail.com (Thomas A) wrote:
>
> much snipped .....
>
> >If you look at the link, there is a quite large difference between
> >coupling and decoupling, and the effects of standing waves in the room
> >acting on the wood floor and in turn the speaker.
>
> I saw no reference to standing waves on the site.
It's missed in the english version. Another link states main room
nodes at 61.5 Hz calulated. The main peak vibration found in the floor
between the speakers are most likely to correspond to this room node.
This peak is also seen close to the speakers, when they are decoupled
from the floor.
> As I mentioned
> >below, the movement is different depending on speakers as heavy
> >cabinet tend to give higher local pressure pressure and reduce
> >frequency and Q of the floor vibration.
>
> According to the un-defined graphics on the referenced site (no details as to
> what/how those pictures were generated) one would have to assume that most of
> the energy from the speaker is transmitted through the feet (or spikes in this
> case.)
No spikes as I can recall, stands are using a tripod stand directly on
the floor and speakers firmly attached to stand or soft feet between
speaker and stand. This link shows another picture with fixed tones.
Partly in Swedish, but the graphs are in English. When coupled, there
is more vibrations in speaker.
http://www.mosaic.fi/markku/vibra.html
> This seems to be contradicted by your later reference where it's said that
> speaker location relative to adjacent room surfaces may have a larger effect.
I do not really know what you are referring to here.
> While I have no general use for spikes the site seems to be, for the most part,
> promoting a solution looking for a problem.
Well, all I can say, spikes are no good.
>
> Whether the vibrations are
> >capable of moving the speaker significantly to be audible, I cannot
> >say, but there is a clear difference.
>
> >The floor flex from energy transmitted from acoustical energy which in
> >turn affects the speaker and other objects. The optimal goal is to
> >have the speaker standing as still as possible.
>
> The only speaker I've ever seen that claimed to move was a Sunfire subwoofer
> which had such a high moving mass driver and tremendous imbalance where people
> have claimed they've made it "walk." However I've not seen this myself and I've
> never seen the Sunfire people perform such a demo at the CES.
>
I don't believe it. If it does, it's cabinet is too light and a poor
speaker. Movement of the cabinet due to action-reaction forces are
miniscule if the speaker is correctly built. As Dick Pierce have
calculated, a weight ratio of driver:cabinet of 1:1000 will guarantee
motion of less than 1:1000 of the speaker cabinet relative to the
driver when speaker is attached to nothing (free floating in air).
Coupling give rise to a resonance which is dependent on the compliance
of speaker/floor interface and the weight of the speaker, and with
spikes this usually happens somewhere in the bass region. Resonance
cause the movements above to be larger than the calculated values
above, when forces act in this region. Measurements with
accelerometers by Ingvar Ohman have shown that the movement is always
higher with spikes than with soft feet having a low resonance. The
range of difference is around 10 dB and sometimes up to 20 dB. I am
quite sure Dick Pierce have performed similar measurements.
> See previous link. It
> >however, also isolates transmission of vibrations from speaker to the
> >floor, which could act as a second speaker with its very large surface
> >area. See
> >
> >http://www.sonicdesign.se/sdfeet.html
> >
> >>
> >> >There would also be a resonance peak of the floor/speaker interface
> >> >and when forces are generated at this resonance, the speaker cabinet
> >> >would move more.
>
> One of your sites suggests that the peak energy is greater and of higher Q with
> decoupling.
No. If you are referring to the high-Q peak higher up in frequency
with soft feet, I cannot comment on. I don't know where this comes
from, but it's only present on one speaker. Mass loading reduce
frequency and lower Q. The peaks in the low bass region when the
speaker is coupled to the floor is significantly lower in frequency
than the 60 hz peak, and the 60 Hz peak is gone.
> >http://www.mosaic.fi/markku/sweeptest.html
>
> Interestingly the data on this site tends to show that energy was higher in
> amplitude and Q when the decouplers were used. And that the placement of the
> speaker and other room artifacts may have had a large effect.
No, not in the speakers - only in the floor at the specific room node.
The goal is to have the speaker as still as possible. They move less
by decoupling. Room acoustics should be treated by other means. The
resonance is higher in the floor with decoupling, but at only one
specific frequency, which corresponds to the main node in the room. It
is more like the measurements between the speakers. That there is
difference of vibration in the floor at different positions should not
be suprising.
>
> As you said before there would be nothing wrong with isolating the speakers but
> the main question is whether one need to bother. I'd say your site references
> don't really make a very good case for that.
If it is audible it could be worth to bother. If it's not, I would
still prefer to have the speaker sitting still.
>
> >I already use the Sonic design isolators. They have a defined
> >resonance below 7 Hz when loaded correctly. My system do not do very
> >deep in bass (35 Hz) so there is no problem. Another system I've
> >listened too have 4 x 15 inch woofers and give sound pressures of 145
> >dB at 17 Hz,
>
> Under what conditions?
See my post to Pierce.
>
> and have its -5 dB point at 10 Hz. Still it uses custom
> >made SD feet and it works fine.
>
> I'd be guessing it would work fine without them as well.
>
It may, or it may not. The blind tests made by the Swedish Acoustical
Society have been positive in hearing differences between decoupling
and coupling. One test included at mechanical lift device that lifted
the speaker 3-4 mm, enabling rather fast switching between soft and
hard coupling. I haven't seen or heard anyone else confirming this in
an independent test, so it's up to anyone to try.
> Subwoofers with heavy passive
> >radiators and too light cabinets are however, not very good to
> >decouple, since the create quite large reaction forces that may cause
> >speakers to move. Such subs may be better to couple to the floor.
>
> But doesn't a moving speaker also decouple itself? The movement is dissipating
> energy, isn't it?
Below resonance of the speaker driver, the forces generated by the
driver are dissipated in the rubber/foam surround. Above resonance the
forces are dissipated in the structure of the cabinet and by the
movement of the cabinet as such. At least that's what I've read.
Thomas
Thomas A
Look at the link below, posted to Pierce. The maximal sound pressure
level of Z-4 is 139 dB, error of me previously, but still
exceptionally high. Don't know what their largest system Z-10 is
capable of though. The place where the sound pressure level
measurements were made is Studio Blue, a recording studio and an
educational center for recording technicians. The Swedish
Audio-technical Society do some of their listening tests in that place
also (blind and double-blind). Ino Audio makes both home audio and
installations for professionals using very special drivers only
designed at Ino. The waiting list to get some of these speakers are up
to 3-4 years, and I'm not sure if they are exported outside Sweden.
Some pictures of the studio can be viewed at
http://www.studioblue.se/Bilder.htm
Thomas
Richard D Pierce
Thomas A <thomas_...@hotmail.com> wrote:
>DPi...@TheWorld.com (Richard D Pierce) wrote in message
>news:<a8g6q...@enews1.newsguy.com>...
>> In article <a8fb2...@enews4.newsguy.com>,
>> Thomas A <thomas_...@hotmail.com> wrote:
>> >
>> >Another system I've listened too have 4 x 15 inch woofers and
>> >give sound pressures of 145 dB at 17 Hz, and have its -5 dB
>> >point at 10 Hz.
>>
>> do 145 dB at 1 meter at 17 Hz, they were doing a pretty good job
>> of SERIOUSLY pulling your leg.
>>
>> Extraordinary!
>>
>
>Ok sorry to give such a "extrordinary claim". My memory from the
>written text was not that good, the actual sound pressure limit was
>139 dB, but here I quote the text from Ino speakers company:
>
>"Our largest bass system Profundus Z-4 is the largest sound-pressure
>generating system in the world. If it would be compared to a
>servo-controlled 10 inch woofer in a closed box, the peak of the
>driver would have to be 200 centimeters to compare to the Z-4. A
>conventional subwoofer thus only produce less than 1/20,000 of the
>sound pressure of Z-4, than can move 75 liters of air peak to peak
>close to its lower frequency limit. A maximal sound pressure of 139 dB
>can be generated to below 20 Hz.
These are advertising claims. These claims, as stated, fly in
the face of the fundamental physics involved. Notice that they
state excursion requirements that are not all that different
than I stated, yet they give NO information about how they
defeat the laws of physics that make those excursions mandatory.
The difference between 145 and 139 dB is minor compared to the
fact that they are making claims of 30-40 dB higher than seems
even feasible. In other words, why worry about a factor of 4,
when they are making claims on the order of a factor of 1000.
(attempting several web searches on the various keywords you
mention reveals nothing, so trhere's no way I can see the
comapnies claims directly).
There are several interesting points in there claims. One, for
example, is about the performance requirements of a
"servo-controlled" 10" woofer and excursion: servo control is
utterely irrelevant to the connection between excursion and
sound pressure level: Whether a woofer is servo-controlled or
not, a piston of a ceretain diameter MUST move a certain
distance to produce a sound pressure level of X and F frequency.
Period.
Methinks they are making grand and wild claims.
>The 139 dB that Z-4 generates is extremely high and many rooms may
>also give 6 dB higher sound pressure because of its walls. World
>famous recording engineer Bertil Alving have measured the system in
>the studio "Studio Blue" and have confirmed the lowest limit to 14 Hz.
>For a test of maximal sound pressure if was measured to 137 dB at 17
>to 55 Hz about 7 meters distance from the speakers. At the mixer
>tables the sound pressure was 134 dB, which corresponds to a sound
>pressure of 145 dB 1 meter from the speakers. On one meter however,
>max sound pressure is in normal cases 139 dB in all normal rooms since
>the impact of room at such distances is minimal."
This statement in itself is telling: at 20 Hz, many rooms will
be operating in pressure mdoe and, in fact, the impact of the
room at ALL distances is far from minimal.
>So the level was lower than I first wrote, but still very high. If you
>want to confirm this, you will have to talk to Bertil Alving who did
>the measurements, or speak directly to Ino Audio.
No, I have to do no such thing. These people are making truly
extraordinary and, in come cases, contradictory claims: it's up
to them to come up with credible evidence to support their truly
extraordinary claims.
Richard D Pierce
Thomas A <thomas_...@hotmail.com> wrote:
>> PLEASE describe this setup! Thanks, Mark
>
>Look at the link below, posted to Pierce.
>
This link takes me to nothing but some pictures. No text, no
measurements, no links.
>The maximal sound pressure
>level of Z-4 is 139 dB, error of me previously, but still
>exceptionally high.
A maximum sound pressure level of 139 dB and a maximum sound
pressure level of 139 dB at 17 Hz are two VERY different
things. For example, 139 dB at 17 Hz requires 138 times longer
excursion that 139 dB at 200 Hz needs (excursion for a given
sound pressure level is proportional to the reciprocal of the
square root of frequency).
Still, waiting for ANY substantiation of these extraordinary
Howard Ferstler
What kind of music are these people recording that would require such
subwoofer performance?
Howard Ferstler
Mark Wilkinson
From: "Stewart Pinkerton" > I guess he means 105dB, although even that would
be pretty impressive
> at 17Hz! Or of course, he could be describing a pressure-loaded
> automobile system................................
>
Grin. Yea, I'd believe anything out of the loud-car audio folks.
Those crazies are cranking over 170db! Insane. Mark
Nousaine
>> much snipped .....
>>
>> >If you look at the link, there is a quite large difference between
>> >coupling and decoupling, and the effects of standing waves in the room
>> >acting on the wood floor and in turn the speaker.
>>
>> I saw no reference to standing waves on the site.
>
>It's missed in the english version. Another link states main room
>nodes at 61.5 Hz calulated. The main peak vibration found in the floor
>between the speakers are most likely to correspond to this room node.
>This peak is also seen close to the speakers, when they are decoupled
>from the floor.
And the data published there shows that the decoupled condition
transmits a great deal more energy to the floor. I am also wondering
how the mV vertical scale relates to physical effect. And, of course,
there's no connection to levels of audibility with any of this
stuff.
>> According to the un-defined graphics on the referenced site (no details as to
>> what/how those pictures were generated) one would have to assume that most of
>> the energy from the speaker is transmitted through the feet (or spikes in this
>> case.)
>
>No spikes as I can recall, stands are using a tripod stand directly on
>the floor and speakers firmly attached to stand or soft feet between
>speaker and stand. This link shows another picture with fixed tones.
>Partly in Swedish, but the graphs are in English. When coupled, there
>is more vibrations in speaker.
Well then how can you say that spikes are bad with no comparative
data?
>
>http://www.mosaic.fi/markku/vibra.html
>
>> This seems to be contradicted by your later reference where it's said that
>> speaker location relative to adjacent room surfaces may have a larger
>> effect.
>
>I do not really know what you are referring to here.
The text on the site suggested that a ceiling condition was
accounting for differences between the two speakers. I'm guessing
that the conditions of the measurements are contributing to
differences and not the inherent decoupling devices.
>
>> While I have no general use for spikes the site seems to be, for the most part,
>> promoting a solution looking for a problem.
>
>Well, all I can say, spikes are no good.
>
>>
>> Whether the vibrations are
>> >capable of moving the speaker significantly to be audible, I cannot
>> >say, but there is a clear difference.
>
>> >The floor flex from energy transmitted from acoustical energy which in
>> >turn affects the speaker and other objects. The optimal goal is to
>> >have the speaker standing as still as possible.
I don't think they move as it is. Decouplers don't affect this in any
way that can be deduced from the data at the referenced sites IMO.
>> The only speaker I've ever seen that claimed to move was a Sunfire subwoofer
>> which had such a high moving mass driver and tremendous imbalance where people
>> have claimed they've made it "walk." However I've not seen this myself and I've
>> never seen the Sunfire people perform such a demo at the CES.
>>
>
>I don't believe it. If it does, it's cabinet is too light and a poor
>speaker. Movement of the cabinet due to action-reaction forces are
>miniscule if the speaker is correctly built. As Dick Pierce have
>calculated, a weight ratio of driver:cabinet of 1:1000 will guarantee
>motion of less than 1:1000 of the speaker cabinet relative to the
>driver when speaker is attached to nothing (free floating in air).
That's what I've been saying. Speaker movement just doesn't occur in
any mounting condition.
>Coupling give rise to a resonance which is dependent on the compliance
>of speaker/floor interface and the weight of the speaker, and with
>spikes this usually happens somewhere in the bass region. Resonance
>cause the movements above to be larger than the calculated values
>above, when forces act in this region. Measurements with
>accelerometers by Ingvar Ohman have shown that the movement is always
>higher with spikes than with soft feet having a low resonance. The
>range of difference is around 10 dB and sometimes up to 20 dB. I am
>quite sure Dick Pierce have performed similar measurements.
>
>> >See previous link. It
>> >however, also isolates transmission of vibrations from speaker to the
>> >floor, which could act as a second speaker with its very large surface
>> >area. See
>> >
>> >http://www.sonicdesign.se/sdfeet.html
>> >
>> >>
>> >> >There would also be a resonance peak of the floor/speaker interface
>> >> >and when forces are generated at this resonance, the speaker cabinet
>> >> >would move more.
>>
>> One of your sites suggests that the peak energy is greater and of higher Q with
>> decoupling.
>
>No. If you are referring to the high-Q peak higher up in frequency
>with soft feet, I cannot comment on. I don't know where this comes
>from, but it's only present on one speaker.
What does that suggest? That decoupling isn't what causes those
differences?
> Mass loading reduce
>frequency and lower Q.
So then decouplers reduce the mass of the speaker raising the
magnitude and frequency of the resonance? But, only some of the
time?
> The peaks in the low bass region when the
>speaker is coupled to the floor is significantly lower in frequency
>than the 60 hz peak, and the 60 Hz peak is gone.
>
>> >http://www.mosaic.fi/markku/sweeptest.html
>>
>> Interestingly the data on this site tends to show that energy was higher in
>> amplitude and Q when the decouplers were used. And that the placement of the
>> speaker and other room artifacts may have had a large effect.
>
>No, not in the speakers - only in the floor at the specific room node.
>The goal is to have the speaker as still as possible. They move less
>by decoupling. Room acoustics should be treated by other means. The
>resonance is higher in the floor with decoupling, but at only one
>specific frequency, which corresponds to the main node in the room. It
>is more like the measurements between the speakers. That there is
>difference of vibration in the floor at different positions should not
>be suprising.
Sure, but it would seem that the decouplers are transmitting more
energy to the floor right next to the speaker where the effect should
be greatest. This is in direct contradiction to your case here. But,
since no one has ever suggested that the effects are audible in
either case, who cares?
>> As you said before there would be nothing wrong with isolating the speakers but
>> the main question is whether one need to bother. I'd say your site references
>> don't really make a very good case for that.
>
>If it is audible it could be worth to bother. If it's not, I would
>still prefer to have the speaker sitting still.
Why would anyone care? But you are entitiled to that opinion.
>> >and have its -5 dB point at 10 Hz. Still it uses custom
>> >made SD feet and it works fine.
>>
>> I'd be guessing it would work fine without them as well.
>>
>
>It may, or it may not. The blind tests made by the Swedish Acoustical
>Society have been positive in hearing differences between decoupling
>and coupling. One test included at mechanical lift device that lifted
>the speaker 3-4 mm, enabling rather fast switching between soft and
>hard coupling. I haven't seen or heard anyone else confirming this in
>an independent test, so it's up to anyone to try.
Do you have a site refence? Also useful to have some detail on how
the tests were conducted.
>
>> >Subwoofers with heavy passive
>> >radiators and too light cabinets are however, not very good to
>> >decouple, since the create quite large reaction forces that may cause
>> >speakers to move. Such subs may be better to couple to the floor.
>>
>> But doesn't a moving speaker also decouple itself? The movement is dissipating
>> energy, isn't it?
>
>Below resonance of the speaker driver, the forces generated by the
>driver are dissipated in the rubber/foam surround. Above resonance the
>forces are dissipated in the structure of the cabinet and by the
>movement of the cabinet as such. At least that's what I've read.
>
>Thomas
So then a speaker with a Fs of 50 hz or 200 Hz doesn't need
decouplers at lower frequencies? Just asking :)
Thomas A
> >written text was not that good, the actual sound pressure limit was
> >139 dB, but here I quote the text from Ino speakers company:
> >
> >"Our largest bass system Profundus Z-4 is the largest sound-pressure
> >generating system in the world. If it would be compared to a
> >servo-controlled 10 inch woofer in a closed box, the peak of the
> >driver would have to be 200 centimeters to compare to the Z-4. A
> >conventional subwoofer thus only produce less than 1/20,000 of the
> >sound pressure of Z-4, than can move 75 liters of air peak to peak
> >close to its lower frequency limit. A maximal sound pressure of 139 dB
> >can be generated to below 20 Hz.
>
> These are advertising claims. These claims, as stated, fly in
> the face of the fundamental physics involved. Notice that they
> state excursion requirements that are not all that different
> than I stated, yet they give NO information about how they
> defeat the laws of physics that make those excursions mandatory.
>
> The difference between 145 and 139 dB is minor compared to the
> fact that they are making claims of 30-40 dB higher than seems
> even feasible. In other words, why worry about a factor of 4,
> when they are making claims on the order of a factor of 1000.
>
> (attempting several web searches on the various keywords you
> mention reveals nothing, so trhere's no way I can see the
> comapnies claims directly).
Ino does not exist on the web, nor do they advertise about their
speakers. They build speakers only on personal order. I can ask Ino
about the technical facts of the drivers and come back to you, if you
wish.
>
> There are several interesting points in there claims. One, for
> example, is about the performance requirements of a
> "servo-controlled" 10" woofer and excursion: servo control is
> utterely irrelevant to the connection between excursion and
> sound pressure level: Whether a woofer is servo-controlled or
> not, a piston of a ceretain diameter MUST move a certain
> distance to produce a sound pressure level of X and F frequency.
> Period.
I shortened the text a bit, and they just exemplified that such
subwoofers are quite common on the market and made a comparison. I
don't know the details of Ino drivers, but they have considerably
larger peak limits than commercial drivers on the market.
>
> Methinks they are making grand and wild claims.
>
> >The 139 dB that Z-4 generates is extremely high and many rooms may
> >also give 6 dB higher sound pressure because of its walls. World
> >famous recording engineer Bertil Alving have measured the system in
> >the studio "Studio Blue" and have confirmed the lowest limit to 14 Hz.
> >For a test of maximal sound pressure if was measured to 137 dB at 17
> >to 55 Hz about 7 meters distance from the speakers. At the mixer
> >tables the sound pressure was 134 dB, which corresponds to a sound
> >pressure of 145 dB 1 meter from the speakers. On one meter however,
> >max sound pressure is in normal cases 139 dB in all normal rooms since
> >the impact of room at such distances is minimal."
>
> This statement in itself is telling: at 20 Hz, many rooms will
> be operating in pressure mdoe and, in fact, the impact of the
> room at ALL distances is far from minimal.
Can't argue with you there, but my translation of the text might have
been poor and I shortened it somewhat.
>
> >So the level was lower than I first wrote, but still very high. If you
> >want to confirm this, you will have to talk to Bertil Alving who did
> >the measurements, or speak directly to Ino Audio.
>
> No, I have to do no such thing. These people are making truly
> extraordinary and, in come cases, contradictory claims: it's up
> to them to come up with credible evidence to support their truly
> extraordinary claims.
So a peer reviewed report is the only option? If not, what would kind
of data would you want so I can prepare questions?
Thomas
Thomas A
> transmits a great deal more energy to the floor. I am also wondering
> how the mV vertical scale relates to physical effect. And, of course,
> there's no connection to levels of audibility with any of this
> stuff.
>
Again, if you are referring to the large peak in the floor with
decoupling has nothing to do with energy from the speaker to the floor
via the speaker stand. It's the acoustical pressure in the room, and
the floor looks like that in nearly every place in the room, except
when it is weight-loaded.
> >
> >No spikes as I can recall, stands are using a tripod stand directly on
> >the floor and speakers firmly attached to stand or soft feet between
> >speaker and stand. This link shows another picture with fixed tones.
> >Partly in Swedish, but the graphs are in English. When coupled, there
> >is more vibrations in speaker.
>
> Well then how can you say that spikes are bad with no comparative
> data?
Coupling do not need to always imply the use spikes, a stand with
small hard feet can be similar. Another article in "Musik och
Ljudteknik", 1991, used spikes and soft feet made of a very thick
carpet. The resonance of the cabinet with spikes was found around 50
Hz, and around 10-15 Hz with the soft feet. The accelerometer was
placed in the upper left corner of the speaker, and the vibrations
where about 10 dB more in the 20-70 Hz range using the spikes.
>
> >
> >http://www.mosaic.fi/markku/vibra.html
> >
> >> This seems to be contradicted by your later reference where it's said that
> >> speaker location relative to adjacent room surfaces may have a larger
> >> effect.
> >
> >I do not really know what you are referring to here.
>
> The text on the site suggested that a ceiling condition was
> accounting for differences between the two speakers. I'm guessing
> that the conditions of the measurements are contributing to
> differences and not the inherent decoupling devices.
>
> >
> >> While I have no general use for spikes the site seems to be, for the most part,
> >> promoting a solution looking for a problem.
> >
> >Well, all I can say, spikes are no good.
> >
> >>
> >
> >I don't believe it. If it does, it's cabinet is too light and a poor
> >speaker. Movement of the cabinet due to action-reaction forces are
> >miniscule if the speaker is correctly built. As Dick Pierce have
> >calculated, a weight ratio of driver:cabinet of 1:1000 will guarantee
> >motion of less than 1:1000 of the speaker cabinet relative to the
> >driver when speaker is attached to nothing (free floating in air).
>
> That's what I've been saying. Speaker movement just doesn't occur in
> any mounting condition.
>
The above statement is when a speaker is free floating in air, not
spiked to flexible wood floor. Totally different situation.
No, all the time.
>
> > The peaks in the low bass region when the
> >speaker is coupled to the floor is significantly lower in frequency
> >than the 60 hz peak, and the 60 Hz peak is gone.
> >
> >> >http://www.mosaic.fi/markku/sweeptest.html
> >>
> >> Interestingly the data on this site tends to show that energy was higher in
> >> amplitude and Q when the decouplers were used. And that the placement of the
> >> speaker and other room artifacts may have had a large effect.
> >
> >No, not in the speakers - only in the floor at the specific room node.
> >The goal is to have the speaker as still as possible. They move less
> >by decoupling. Room acoustics should be treated by other means. The
> >resonance is higher in the floor with decoupling, but at only one
> >specific frequency, which corresponds to the main node in the room. It
> >is more like the measurements between the speakers. That there is
> >difference of vibration in the floor at different positions should not
> >be suprising.
>
> Sure, but it would seem that the decouplers are transmitting more
> energy to the floor right next to the speaker where the effect should
> be greatest. This is in direct contradiction to your case here. But,
> since no one has ever suggested that the effects are audible in
> either case, who cares?
Well you see the room node reflected as floor vibration, as you would
see at every place in the room. Nothing strange with this.
>
> >> As you said before there would be nothing wrong with isolating the speakers but
> >> the main question is whether one need to bother. I'd say your site references
> >> don't really make a very good case for that.
> >
> >If it is audible it could be worth to bother. If it's not, I would
> >still prefer to have the speaker sitting still.
>
> Why would anyone care? But you are entitiled to that opinion.
>
> >> >and have its -5 dB point at 10 Hz. Still it uses custom
> >> >made SD feet and it works fine.
> >>
> >> I'd be guessing it would work fine without them as well.
> >>
> >
> >It may, or it may not. The blind tests made by the Swedish Acoustical
> >Society have been positive in hearing differences between decoupling
> >and coupling. One test included at mechanical lift device that lifted
> >the speaker 3-4 mm, enabling rather fast switching between soft and
> >hard coupling. I haven't seen or heard anyone else confirming this in
> >an independent test, so it's up to anyone to try.
>
> Do you have a site refence? Also useful to have some detail on how
> the tests were conducted.
I cannot say anymore at the moment. The tests were made more than 10
years ago, when I was not a member of the Acoustical Society. I have
not been able to get all the back subscriptions yet.
>
> >
> >> >Subwoofers with heavy passive
> >> >radiators and too light cabinets are however, not very good to
> >> >decouple, since the create quite large reaction forces that may cause
> >> >speakers to move. Such subs may be better to couple to the floor.
> >>
> >> But doesn't a moving speaker also decouple itself? The movement is dissipating
> >> energy, isn't it?
> >
> >Below resonance of the speaker driver, the forces generated by the
> >driver are dissipated in the rubber/foam surround. Above resonance the
> >forces are dissipated in the structure of the cabinet and by the
> >movement of the cabinet as such. At least that's what I've read.
> >
> >Thomas
>
> So then a speaker with a Fs of 50 hz or 200 Hz doesn't need
> decouplers at lower frequencies? Just asking :)
Correct. It would be irrelevant for higher Fs, since forces would
never be generated close to the fundamental resonance of the cabinet.
Thomas
Thomas A
> In article <a8hv0...@enews4.newsguy.com>,
> Thomas A <thomas_...@hotmail.com> wrote:
> >> PLEASE describe this setup! Thanks, Mark
> >
> >Look at the link below, posted to Pierce.
> >
> >http://www.studioblue.se/Bilder.htm
>
> This link takes me to nothing but some pictures. No text, no
> measurements, no links.
>
> >The maximal sound pressure
> >level of Z-4 is 139 dB, error of me previously, but still
> >exceptionally high.
>
> A maximum sound pressure level of 139 dB and a maximum sound
> pressure level of 139 dB at 17 Hz are two VERY different
> things. For example, 139 dB at 17 Hz requires 138 times longer
> excursion that 139 dB at 200 Hz needs (excursion for a given
> sound pressure level is proportional to the reciprocal of the
> square root of frequency).
>
> Still, waiting for ANY substantiation of these extraordinary
> claims.
Ok I got an answer from Ino. The linear peak limit of the drivers are
50 mm. But the subwoofers have other feauters making them capable of
pumping more air than that. The constructor at Ino, Ingvar Ohman, will
be happy to answer all your questions on mail. The mail address is
The room which the measurements were made is also special designed for
the woofer system. He will be happy to tell you all details about the
system.
Thomas
Mark Wilkinson
From: "Nousaine" <nous...@aol.com>
> True. I have a system with 8 fifteen inch 23-mm Xmax drivers mounted
> in an infinite baffle arrangement which will produce 120 dB at 2
> meters over the 12-62 Hz range when powered by a Crown MacroTech 5000
> in a real room.
>
I believe this is the most powerful setup I've heard described, from someone
who is after qualility and volume. Way to go!
I'm very curious about the remainder of your speakers -- I'm assuming they
can match or exceed the volume of your subs -- and there's not a lot of
hi-fi gear (that I've found) that can honestly put out mid 120db. Not
trying to pry, I'm in the process of filling a fairly large room. The best
combination of quality/volume I've encountered is from Meyersound. I'd like
to give Tannoy's pro line a listen, as well -- and anything you might
suggest.
Also, I've been willing to let bass go f-3 at 30hz or below. How much does
the bottom octave (16-32) add? I've heard one unexpected benefit is the
feeling or sense of loudless is increased, without turning up the volume.
This would be ideal, if true. The only cost effective route to 16hz that
I've found (for a 12,000 cu ft room) would be a few of Servodrives
Contrabass units. I'm curious what you found, and why you elected to go
custom.
Hopefully you don't mind describing your system. I've posted this to the NG
because I feel everyone would be interested, but if you'ld rather not be so
public, please email. Thx, Mark
Stewart Pinkerton
A) wrote:
>DPi...@TheWorld.com (Richard D Pierce) wrote in message news:<a8ib3...@enews3.newsguy.com>...
>> In article <a8hv0...@enews4.newsguy.com>,
>> Thomas A <thomas_...@hotmail.com> wrote:
>> >> PLEASE describe this setup! Thanks, Mark
>> >
>> >Look at the link below, posted to Pierce.
>> >
>> >http://www.studioblue.se/Bilder.htm
>>
>> This link takes me to nothing but some pictures. No text, no
>> measurements, no links.
>>
>> >The maximal sound pressure
>> >level of Z-4 is 139 dB, error of me previously, but still
>> >exceptionally high.
>>
>> A maximum sound pressure level of 139 dB and a maximum sound
>> pressure level of 139 dB at 17 Hz are two VERY different
>> things. For example, 139 dB at 17 Hz requires 138 times longer
>> excursion that 139 dB at 200 Hz needs (excursion for a given
>> sound pressure level is proportional to the reciprocal of the
>> square root of frequency).
>>
>> Still, waiting for ANY substantiation of these extraordinary
>> claims.
>
>Ok I got an answer from Ino. The linear peak limit of the drivers are
>50 mm. But the subwoofers have other feauters making them capable of
>pumping more air than that.
Oh, really? What 'features' would extend this from 50mm to the
required 500mm? :-)
Can we take it that the surround is made from compressed bullshit, and
the coil gap is cooled by snake oil?
>The constructor at Ino, Ingvar Ohman, will
>be happy to answer all your questions on mail. The mail address is
>
>inoa...@hotmail.com
This should be fun!
>The room which the measurements were made is also special designed for
>the woofer system. He will be happy to tell you all details about the
>system.
Would it by any chance have a voluime of about 5 cubic metres? :-)
Richard D Pierce
Thomas A <thomas_...@hotmail.com> wrote:
>> There are several interesting points in there claims. One, for
>> example, is about the performance requirements of a
>> "servo-controlled" 10" woofer and excursion: servo control is
>> utterely irrelevant to the connection between excursion and
>> sound pressure level: Whether a woofer is servo-controlled or
>> not, a piston of a ceretain diameter MUST move a certain
>> distance to produce a sound pressure level of X and F frequency.
>> Period.
>
>I shortened the text a bit, and they just exemplified that such
>subwoofers are quite common on the market and made a comparison. I
>don't know the details of Ino drivers, but they have considerably
>larger peak limits than commercial drivers on the market.
"considerably larger?" Well, to achieve 139 dB at 17 Hz as
claimed, it would not have to be "considerably larger," but
"fantastically, outrageously, even, well, extraordinarily"
larger. It would have to be on the order of 300 mm. That's A
THIRD OF A METER!
Ino wants us to believe they have a 15" woofer with an excursion
of 12 inches? That's what they're asking IF they claim 139 dB at
17 Hz at 1 meter out of 4 15" woofers.
>> >So the level was lower than I first wrote, but still very high. If you
>> >want to confirm this, you will have to talk to Bertil Alving who did
>> >the measurements, or speak directly to Ino Audio.
>>
>> No, I have to do no such thing. These people are making truly
>> extraordinary and, in come cases, contradictory claims: it's up
>> to them to come up with credible evidence to support their truly
>> extraordinary claims.
>
>So a peer reviewed report is the only option? If not, what would kind
>of data would you want so I can prepare questions?
No, I didn't say that.
I would want to, first, see them state on paper the claim that
these devices do, indeed, produce 139 dB at 17 Hz at a distance
of 1 meter. And if the URL you cited shows the woofers, as it
seems to do, have them kindly explain to us how a 15" woofer can
move 12" without banging into the grill which seems tightly
screwed over the fronts of them.
Or have them explain how they can make a claim that completely
ignores the basic physics of the devices.
Or, maybe, someone is not quoting them right and they are not
claiming 139 dB at 17 Hz.
Because is is PHYSICALLY impossible for the speakers pictured on
that URL to produce that kind of performance. Period.
Thomas A
They do not require all that performance. They Studio makes very few
records, it's mainly an educational center for recording engineers.
The system has been built up to be as distortionfree as possible,
hence the very high overload limit.
Thomas
Thomas A
> Thomas A <thomas_...@hotmail.com> wrote:
> >> PLEASE describe this setup! Thanks, Mark
> >
> >Look at the link below, posted to Pierce.
> >
> >http://www.studioblue.se/Bilder.htm
>
> This link takes me to nothing but some pictures. No text, no
> measurements, no links.
The purpose of the link was not to show any data, just the interior of
the studio.
> >The maximal sound pressure
> >level of Z-4 is 139 dB, error of me previously, but still
> >exceptionally high.
>
> A maximum sound pressure level of 139 dB and a maximum sound
> pressure level of 139 dB at 17 Hz are two VERY different
> things. For example, 139 dB at 17 Hz requires 138 times longer
> excursion that 139 dB at 200 Hz needs (excursion for a given
> sound pressure level is proportional to the reciprocal of the
> square root of frequency).
>
> Still, waiting for ANY substantiation of these extraordinary
> claims.
If you can wait some more when I get the reply from Ino, I will
substantiate some more with how much linear excursion that can be
obtained from these drivers. What I can say from the text at the
moment is that the active membrane diameter for each of these drivers
is 33 centimeters. In their smaller standard driver, the active
diameter is 17.3 centimeters (=6.8 inch) but should correspond to a 9
inch woofer when compared to values given for commercial woofers.
Assuming (me assuming here) that the ratio would be the same for their
extreme bass woofer, the size of the woofer would be no less than 17
inch, not 15 inch as as said previously, if it would be given same
values as for standard woofers. The other info I can extract from the
text is that it use a non-conventional motorsystem with an
extreme-linear peak to peak limit. But I'll come back to you to give
you the further data.
Thomas
Thomas A
> Thomas A <thomas_...@hotmail.com> wrote:
> >> PLEASE describe this setup! Thanks, Mark
> >
> >Look at the link below, posted to Pierce.
> >
> >http://www.studioblue.se/Bilder.htm
>
> This link takes me to nothing but some pictures. No text, no
> measurements, no links.
>
> >The maximal sound pressure
> >level of Z-4 is 139 dB, error of me previously, but still
> >exceptionally high.
>
> A maximum sound pressure level of 139 dB and a maximum sound
> pressure level of 139 dB at 17 Hz are two VERY different
> things. For example, 139 dB at 17 Hz requires 138 times longer
> excursion that 139 dB at 200 Hz needs (excursion for a given
> sound pressure level is proportional to the reciprocal of the
> square root of frequency).
>
> Still, waiting for ANY substantiation of these extraordinary
> claims.
Here is a translation of a mail I got from Ino. I apologize for my
English.
"A speaker with 4 X 15 inch membranes with an excursion limit of 5 cm
can give 8.55 dm2 * 0.5 dm * 4 = 17 liters of air. At tuning frequency
there is an acoustical gain (at Qh = 7) of about 6 times relative to
the frequency just above tuning. 17 * 6 = 102 liters, or 0.102 m3. In
reality the speaker is less effective and only give 80 liters peak to
peak. The room can be calculated from floor is 4 * 5 meters and from
floor ceiling is 2.25 meters, which is 45 m3. 1 pa = 1/100,000
atmospheres = 94 dB SPL. A "pump" capacity of 80 liters is similar to
about 30 liters RMS, that gives air pressure in the room of 1.428
*100,000 * 0.03/45 = 95.2 pa, or 39.6 dB over one pascal. 94 + 39.6 =
133 dB is the lowest sound pressure limit that the system can generate
in the whole listening room. Thus also at 5 meters from the speakers,
but it does not end there. As a matter of fact, this is true at DC. At
higher frequencies, even larger sound pressures can be generated.
Also, the standard is that sound pressure level is given at one meter
from the speakers."
Thomas
Thomas A
As I recently spoke to Ino, both the room and woofers in the Studio
are special-designed to work together. The woofer system is only
installed and built at place and is not sold as a separate unit. The
room is thus a part of the system.
Thomas
Nousaine
>----- Original Message -----
From: "Nousaine" <nous...@aol.com>
>> True. I have a system with 8 fifteen inch 23-mm Xmax drivers mounted
>> in an infinite baffle arrangement which will produce 120 dB at 2
>> meters over the 12-62 Hz range when powered by a Crown MacroTech 5000
>> in a real room.
>>
>
>I believe this is the most powerful setup I've heard described, from someone
>who is after qualility and volume. Way to go!
>
>I'm very curious about the remainder of your speakers -- I'm assuming they
>can match or exceed the volume of your subs -- and there's not a lot of
>hi-fi gear (that I've found) that can honestly put out mid 120db.
Actually I had to add a pair of bandpass woofers to my left/right
front channels to avoid the obvious mid-bass compression that would
occur when the subwoofer was mated directly to 6.5-inch two way
systems.
But the 120-dB output level is purely academic. The subwoofer only
gets played at maximum SPL when measuring full output capability.
There is no program material that I have which requires 120 dB at any
frequency. At frequencies above the subwoofer range they are also
dangerous to your hearing.
To test full output I needed a 5000-watt amplifier. For everyday use
a 250-watt per channel two channel device plays the subwoofer loudly
enough that a 20 Hz sine wave will modulate voices of people 4 meters
away.
My goal was to make a subwoofer system that would play any known or
reasonably likely low frequency program material with no dynamic
limits. The project began when I measured several high output
homebrew subwoofer systems during the mid-90s and found that they had
significantly more extended and robust output than either the best
available commercial units or my 18-inch 25-foot custom unit.
So when I moved into a new house the project just took on a life of
its own. You can see the system in the June 99 Stereo Review.
The system uses all powered speakers including 4 surrounds and a
behind the perf-screen center. So there are 6 main channels, 2 of
which also employ a supplemental woofer.
The room itself has open architecture and a volume of 7600 cubic
feet. The subwoofer is an infinite baffle basement mount. It requires
about 18-dB of boost at 12 Hz to measure flat to that frequency at
the listening position.
Not
>trying to pry, I'm in the process of filling a fairly large room. The best
>combination of quality/volume I've encountered is from Meyersound. I'd like
>to give Tannoy's pro line a listen, as well -- and anything you might
>suggest.
>
>Also, I've been willing to let bass go f-3 at 30hz or below. How much does
>the bottom octave (16-32) add?
Depends on what you play. With the advent of digital storage media
there are now many recordings with powerful frequency content down to
7 Hz or so. Also recall that organs with a 16-Hz fundamental may not
be fully resolved with a unit that is half power at that frequency.
I've heard one unexpected benefit is the
>feeling or sense of loudless is increased, without turning up the volume.
Yes there is often an increased sense of spaciousness and the
apparent bass level is enhanced at lower listening levels
considerably.
>This would be ideal, if true. The only cost effective route to 16hz that
>I've found (for a 12,000 cu ft room) would be a few of Servodrives
>Contrabass units. I'm curious what you found, and why you elected to go
>custom.
Simply because there were no commercial units available that would do
the job. The Contrabass pieces also have the drive motor noise issue
plus huge cabinets.
>Hopefully you don't mind describing your system. I've posted this to the NG
>because I feel everyone would be interested, but if you'ld rather not be so
>public, please email. Thx, Mark
If you have more detailed questions please email me.
Thomas A
See post above. For more info, contact Ingvar Ohman at Ino. I will
end my part of the thread here.
Thomas
Thomas A
> >Ok I got an answer from Ino. The linear peak limit of the drivers are
> >50 mm. But the subwoofers have other feauters making them capable of
> >pumping more air than that.
>
> Oh, really? What 'features' would extend this from 50mm to the
> required 500mm? :-)
There is an acoustical gain of a factor of 6 at tuning. The drivers
are very special making tuning extremely linear, which is required to
achive such high SPL.
>
> Can we take it that the surround is made from compressed bullshit, and
> the coil gap is cooled by snake oil?
ok I saw you smileys, but this was no fun. Please...better to wait
saying anything before you have all the data, isn't it?
>
> >The constructor at Ino, Ingvar Ohman, will
> >be happy to answer all your questions on mail. The mail address is
> >
> >inoa...@hotmail.com
>
> This should be fun!
Did you have fun? ;-)
>
> >The room which the measurements were made is also special designed for
> >the woofer system. He will be happy to tell you all details about the
> >system.
>
> Would it by any chance have a voluime of about 5 cubic metres? :-)
Thomas
Richard D Pierce
Thomas A <thomas_...@hotmail.com> wrote:
>> >
>> >Ok I got an answer from Ino. The linear peak limit of the drivers are
>> >50 mm. But the subwoofers have other feauters making them capable of
>> >pumping more air than that.
>>
>> Oh, really? What 'features' would extend this from 50mm to the
>> required 500mm? :-)
>
>are very special making tuning extremely linear, which is required to
>achive such high SPL.
Let's explore this claim. The issue of linearity simply
determines whether the motion is distortion-producing or not.
The issue of linearity does not contronute to the ultimate SPL
limit in any substantive way (except, indeed, for the fact that
if the motion is NON-linear, the utlimate output level could be
higher because of the presence of distortion products.)
That being said, 50 mm of excursion with 4 15" woofers, assuming
absolute perfect linearity over its entire distance and assuming
this is the conventional one-way excursion (i.e., no
peak-to-peak, meaning the peak-to-peak excursion is 100 mm,
rather an extraordibary claim), will buy you, at most, 124 dB of
SPL at 17 Hz.
If Ino means the peak-to-peak excursion limit is 50 mm, then the
system output is limited to 118 dB.
FAR from the extraordinary claim of 139 dB.
Stewart Pinkerton
A) wrote:
>> >
>> >Ok I got an answer from Ino. The linear peak limit of the drivers are
>> >50 mm. But the subwoofers have other feauters making them capable of
>> >pumping more air than that.
>>
>> Oh, really? What 'features' would extend this from 50mm to the
>> required 500mm? :-)
>
>There is an acoustical gain of a factor of 6 at tuning. The drivers
>are very special making tuning extremely linear, which is required to
>achive such high SPL.
Sorry, this is balderdash. Even the most riduculously excessive tuning
such as you quote above (a real system with a Qts of 6 would sound
*horrendous*, totally 'one-note' bass!), has nothing to do with the
requirement that large volumes of air be moved to achieve the quoted
SPLs. This is totally outwith the compass of *any* 12" driver. As
noted, the drivers would need to move more than 100% of their diameter
at 20-30Hz!
>> Can we take it that the surround is made from compressed bullshit, and
>> the coil gap is cooled by snake oil?
>
>ok I saw you smileys, but this was no fun. Please...better to wait
>saying anything before you have all the data, isn't it?
I already *have* all the data required to dismiss these ridiculous
claims - 4 x 12" drivers are simply *not* capable of producing the
quoted SPL level, or indeed a tenth of it!
>> >The constructor at Ino, Ingvar Ohman, will
>> >be happy to answer all your questions on mail. The mail address is
>> >
>> >inoa...@hotmail.com
>>
>> This should be fun!
>
>Did you have fun? ;-)
Reading your post? Absolutely! :-)
No reply as yet to e-mail request for information.
>> >The room which the measurements were made is also special designed for
>> >the woofer system. He will be happy to tell you all details about the
>> >system.
>>
>> Would it by any chance have a voluime of about 5 cubic metres? :-)
>
>Thomas
>
--
Richard D Pierce
Thomas A <thomas_...@hotmail.com> wrote:
>> >
>> >Ok I got an answer from Ino. The linear peak limit of the drivers are
>> >50 mm. But the subwoofers have other feauters making them capable of
>> >pumping more air than that.
>>
>> Oh, really? What 'features' would extend this from 50mm to the
>> required 500mm? :-)
>
>There is an acoustical gain of a factor of 6 at tuning.
IF that claim were true, that gain of 6 could, at the very most,
account for 8 dB of increased output.
To the claim itself, the cabinets pictured are quite
conventional vented systems. The claim of "gain at tuning" is
either a misundertsanding of how these things work, or an
outright fabrication.
The "gain" in a tuned enclosure is NOT something applies to the
system. A reflex system achives its end by using an overdamped
and thus slightly more efficient driver in an enclosure of some
size. The "gain" comes from the fact that at the tuning
frequency, the otherwise overdamped output of the driver is
REPLACED (not augmented) by the output of the port. This raises
the output of the system as a whole in the region of tuning (and
nowhere else), and providing an extended flat response to a
system that would otherwise have a drooping response in the low
end.
Mr. Ino may be claiming something else, but his claims, in the
face of this data you've provided, seem more and more
outrageous. He's asking us to believe he's suspended the
fundamental laws of physics. He's not the first to do so in the
loudspeaker business, but there has YET to be a first person to
successfully pull such a stunt off, and, frankly, I give him no
better a chance than anyone else.
>The drivers
>are very special making tuning extremely linear, which is required to
>achive such high SPL.
The made NO claim of linearity. Regardless, an excursion of 50
mm is still FAR too small to account for their extraordinary and
outrageous claim. If the excursion was PERFECTLY linear over 50
mm, it's STILL a factor of 10 below the minimum required to
achieve the claimed sound level. NO amount of linearity is EVER
going to make 50 mm behave like 500 mm.
>> Can we take it that the surround is made from compressed bullshit, and
>> the coil gap is cooled by snake oil?
>
>ok I saw you smileys, but this was no fun. Please...better to wait
>saying anything before you have all the data, isn't it?
But, as the data flows in, the claims look more and more
outrageous and unlikely.
Unless the "designer " is willing to show up with a speaker that
implements his outrageous claims, to allow another party to
verify his claims, they must considered as unsubstantiated,
extraordinary and, at this point, outrageous and incredible.
The bruden of supporting these claims is his. It's not mine or
anyone else. He can claim anything he wants. He has to prove it.
Thomas A
> In article <a8p5v4$eoh$1...@bourbaki.localdomain>,
> Thomas A <thomas_...@hotmail.com> wrote:
> >> >
> >> >Ok I got an answer from Ino. The linear peak limit of the drivers are
> >> >50 mm. But the subwoofers have other feauters making them capable of
> >> >pumping more air than that.
> >>
> >> Oh, really? What 'features' would extend this from 50mm to the
> >> required 500mm? :-)
> >
> >The drivers
> >are very special making tuning extremely linear, which is required to
> >achive such high SPL.
>
> Let's explore this claim. The issue of linearity simply
> determines whether the motion is distortion-producing or not.
> The issue of linearity does not contronute to the ultimate SPL
> limit in any substantive way (except, indeed, for the fact that
> if the motion is NON-linear, the utlimate output level could be
> higher because of the presence of distortion products.)
But if the excursion of the driver at tuning is damped (it is, isn't
it), and you feed the driver with power to it's excursion limit at the
tuning frequency, there need to be a very linear tuning to be able to
produce high SPL without distorsion. And a powerful driver.
> That being said, 50 mm of excursion with 4 15" woofers, assuming
> absolute perfect linearity over its entire distance and assuming
> this is the conventional one-way excursion (i.e., no
> peak-to-peak, meaning the peak-to-peak excursion is 100 mm,
> rather an extraordibary claim), will buy you, at most, 124 dB of
> SPL at 17 Hz.
>
> If Ino means the peak-to-peak excursion limit is 50 mm, then the
> system output is limited to 118 dB.
>
> FAR from the extraordinary claim of 139 dB.
I have not seen any comments to the calculation quoted from Ino in the
post below, just your 118 dB number.
Thomas A
> In article <a8p5v4$eoh$1...@bourbaki.localdomain>,
> Thomas A <thomas_...@hotmail.com> wrote:
> >> >
> >> >Ok I got an answer from Ino. The linear peak limit of the drivers are
> >> >50 mm. But the subwoofers have other feauters making them capable of
> >> >pumping more air than that.
> >>
> >> Oh, really? What 'features' would extend this from 50mm to the
> >> required 500mm? :-)
> >
> >There is an acoustical gain of a factor of 6 at tuning.
>
> IF that claim were true, that gain of 6 could, at the very most,
> account for 8 dB of increased output.
>
> To the claim itself, the cabinets pictured are quite
> conventional vented systems. The claim of "gain at tuning" is
> either a misundertsanding of how these things work, or an
> outright fabrication.
>
> The "gain" in a tuned enclosure is NOT something applies to the
> system. A reflex system achives its end by using an overdamped
> and thus slightly more efficient driver in an enclosure of some
> size. The "gain" comes from the fact that at the tuning
> frequency, the otherwise overdamped output of the driver is
> REPLACED (not augmented) by the output of the port. This raises
> the output of the system as a whole in the region of tuning (and
> nowhere else), and providing an extended flat response to a
> system that would otherwise have a drooping response in the low
> end.
Ok, now it's me asking here, not Ino. As I understand it, the output
of the driver is reduced (and hence its excursion) at tuning and
replaced by the port (never said it was augmented). Again, as I
understand it the reduction of the drivers excursion at tuning is a
sort of gain, since the driver can be fed with much more power before
it reaches it maximal excursion (at tuning). So if this gain is a
factor of six relative to about half an octave above tuning frequency,
it means that it would simulate air volumes coming from 300 mm
excursion. True or not?
> Mr. Ino may be claiming something else, but his claims, in the
> face of this data you've provided, seem more and more
> outrageous. He's asking us to believe he's suspended the
> fundamental laws of physics. He's not the first to do so in the
> loudspeaker business, but there has YET to be a first person to
> successfully pull such a stunt off, and, frankly, I give him no
> better a chance than anyone else.
Well I can see that, but do you care to comment on the calculations
given by Ino in the other post?
[quoted text deleted -- deb]
Thomas A
> On Sun, 07 Apr 2002 10:10:56 GMT, thomas_...@hotmail.com (Thomas
> A) wrote:
>
> >> >
> >> >Ok I got an answer from Ino. The linear peak limit of the drivers are
> >> >50 mm. But the subwoofers have other feauters making them capable of
> >> >pumping more air than that.
> >>
> >> Oh, really? What 'features' would extend this from 50mm to the
> >> required 500mm? :-)
> >
> >There is an acoustical gain of a factor of 6 at tuning. The drivers
> >are very special making tuning extremely linear, which is required to
> >achive such high SPL.
>
> Sorry, this is balderdash. Even the most riduculously excessive tuning
> such as you quote above (a real system with a Qts of 6 would sound
> *horrendous*, totally 'one-note' bass!), has nothing to do with the
> requirement that large volumes of air be moved to achieve the quoted
> SPLs. This is totally outwith the compass of *any* 12" driver. As
> noted, the drivers would need to move more than 100% of their diameter
> at 20-30Hz!
There is nothing I said that would give a "one-note bass". If the
drivers excursion is damped at tuning, there would be an possibility
to increase power to the driver at tuning to drive it to its excursion
limit. Most of the air will still the coming through the port, true or
not? The amount of air pumped will thus be higher than calculated from
4 x 15 inch drivers with an excursion limit of 5 cm AT TUNING. The SPL
half and octave above tuning will be lower (since the excursion
naturally increases). But the amount of air required will be slightly
lower due to the higher frequency.
>
> >> Can we take it that the surround is made from compressed bullshit, and
> >> the coil gap is cooled by snake oil?
> >
> >ok I saw you smileys, but this was no fun. Please...better to wait
> >saying anything before you have all the data, isn't it?
>
> I already *have* all the data required to dismiss these ridiculous
> claims - 4 x 12" drivers are simply *not* capable of producing the
> quoted SPL level, or indeed a tenth of it!
Care to comment on the calculations below?
"A loudspeaker with four 15 inch woofers with an excursion limit of 5
cm each can give 8.55 dm2 * 0.5 dm * 4 = 17 liters of air. At tuning
frequency there is an acoustic gain (at Qh = 7) of about 6 fold
relative to the frequency about half an octave above tuning. 17 * 6 =
102 liters, or 0.102 dm3. I reality the efficiency is lower, "only"
80 liters peak to peak. A room with dimensions 4 * 5 * 2.25 meters
will be 45 m3. 1 pa = 1/100,000 atmospheres = 94 dB sound pressure. A
pump capacity of 80 liters is equal to 28.28 liters RMS, which give
air pressure changes of 1.428 * 100,000 * 0.0283/45 = 89.8 pa,or 39
dB over one pascal. 94 + 39 = 133 dB is the minimal sound pressure
that on theroretical means will be produced in the entire room, i.e.
even 5 meters from the speakers. The story does not end there; at
higher frequencies considerably higher soundpressures can be
generated. Not seldom 10-20 dB more at room resonances. The standard
is also that the sound pressure is specified at one meter from the
speaker."
Mark Wilkinson
> measured at a conventional 1 meter, 145 dB SPL tells us that the
> source is producing 2000 ACOUSTIC WATTS, assuming half-space
> radiation.
>
> TWO THOUSAND ACOUSTIC WATTS! That's a TRULY extraordinary claim.
>
I think you'll appreciate this ... there is a subwoofer project going on at
a prosound bulletin board ... accomplished designers collaborating together.
Horn loaded, 6 box configuration predicted to produce over
3 ACOUSTIC HORSEPOWER! f-3 28hz
Dude! Mark
Marin Weigel
yes the Sunfire happily wanted to walk across the room - even loaded with plenty
additional weight.
Standing on it while playing some 16 Hz Organpipe at normal listening level (ca. 95
dB including all the rest of the spectrum, which was quite busy as well) got you
some decent foot-massage while having a sightseeing tour of your listening room -
I'm not exaggerating!!!
The only fix was to find appropriate decoupling feet in conjunction with the right
amount of additional weight.
Final setup were four conical sorbothane footers (45 Shore, ca 2cm dia. and 3cm
high)) screwed firmly into the bottom and a concrete slab of about 15 Kg, coupled
to the top via four small patches of silicon rubber mat.
This way, the Sunfire stayed put under all conditions and only wobbled a bit when
driven with a sinewave-generator to ca. 5 Hz, which seemed to be the resonance of
the setup described above. Some other sinusoidal test-frequencies above that 5 Hz
at max. attainable SPL's generated tiny vibrations, that could only be felt when a
finger was gently applied to the enclosure.
This tweak made the Sunfire's deep bass performance first rate, and only then could
I properly integrate it with my then Magnepan MG2.6R speakers.
Happy listening, Marin
> SNIP
> The only speaker I've ever seen that claimed to move was a Sunfire subwoofer
> which had such a high moving mass driver and tremendous imbalance where people
> have claimed they've made it "walk." However I've not seen this myself and I've
> never seen the Sunfire people perform such a demo at the CES.
> SNIP
Ingvar G. Oehman
Hallo everyone!
Ingvar G. Öhman at Ino Audio here. I would like to do a single
attempt to inform mr Pierce (who seems to be a man of accurate
knowleadge to grasp the acoustic facts needed to understand)
of the design, reasons and physics explaining the claims we
have made (139 dB @ 20 Hz (not 145 dB @ 17 Hz!), 1 metre).
However, in doing so, I will have to criticise some of mr
Pierce's statements, in very few cases for beeing physically
incorrect, but for beeing assumptions not valid.
First in your response you wrote: "Assuming, for the moment,
the sound pressure level claimed is measured at a conventional
1 meter, 145 dB SPL tells us that the source is producing 2000
ACOUSTIC WATTS, assuming half-space radiation."
Well, assuming halv space radiation at 20 Hz in a room is
stupid, would you not agree?
All rooms I have experiensed have seartainly had both floor
and backwall. Actually, they've had sidewalls to! So your
assumption is about 18 dB off! (64 times.)
Apart from that, I have never claimed 145 dB, but 139 dB,
which is another 6 dB (4 times power ratio which make 256 times
togather) down fron 145 dB. So the actual acoustic output is in
fact not 2000 watts as you say, but 256 times lower. i.e approxi-
matly 80 W.
Now, since the true system input power of the Profundus Z-4
is around 6000 W, we end up with an efficiency of only 80/6000,
a little bit over one procent. This is in fact not all that
high, especially considering the size of the system (more than
one kubic metre = 1000 litres). But producing extremly low
frequencys takes it's tribute. The ratio between efficiency,
box size and lower frequency extension is determened by the
laws of nature. So even if 1,5% seems kind of low for such a
large system, the efficincy of Profundus Z-4 is less than
1,5 dB from the theoretical limit.
80 watts is still an extreme output power, I agree, about
four times more than a full symphonic orchestra generating
about 20 watts (20 - 20 000 Hz playing FFF!). But that is the
whole idea with this system - to be adequate, always!
Another thing worth pointing out is that it is in fact silly
to talk about acoustic output power (well, I did it also, but
only because you did it first! :-), since the acoustic load
impedance in the region below 80 Hz is far from real, it is
in fact extremly reactive.
When producing 139 dB sound pressure one metre from the
speaker, due to the reactive loading no way near 80 watts is
produced. This is text book knowleadge, known by anyone
working with acoustics. You should think it through, I think.
Or perhaps you agree already?
When it comes to pumping capacity, it is not easy to determine
an exact value necesarry to produce 139 dB, since it depends so
much on the loading, but I think we can agree on something right
under 80 liters p-p at 20 Hz in a room with supporting walls but
which is non sealed. Right?
At higher frequenses, smaller strokes are needed. In a non
reactive loading, the proportionality is (1/frequency)^2. So if
80 liters is needed at 20 Hz, only 20 liters is needed at 40 Hz.
and at 80 Hz, the necesarry pumpcapacity is 5 liters. Still text-
book knowleadge, so I hope you agree so far.
If Profundus Z-4 were a closed system, a stroke of around
12" would be needed, You are right, but it is not! I can not
see the reason why you speculate again? Profundus Z-4 is not a
closed system but a tuned system!
In fact the measured stroke of the ports at full power 20 Hz
is close to one metre, 12" is far from enough since the port
area is significantly smaller than the membrane area. The driver
however, have a linear stroke of 2" "only". The ports are quite
big by the way, the combined area corresponds to a port with 12"
diametre. To allow for the extreme flow however (not far from
60m/s, almost twice the air flow speed of any "normal" extreme
bass reflex system"), the combined flare diametre is close to
20". The prots are in fact very big. Feel free to amuse yourself
by calculating the pumping capacity, if you are in doubt.
Conclusion
If you have further questions in the future mr Pierce, about Ino
Audios Profundus Z-4 system, please email me directly instead
of making a fool of yourself again (inoa...@hotmail.com).
Or make a fool of yourself if you like! I do not care. But I
will not respond to any further low level criticism based on
false assumptons. If you want to say something, first get the
facts straight! You are obviously not ignorant, on the contrary.
Normally I would recommend everyone to listen to what you have
to say, but this time you are way of!
Best regards, Ingvar Öhman, Ino Audio.
PS. I hope everyone will overlook my faulty English. I am not
the language person I'd like to be.
Richard D Pierce
Ingvar G. Oehman <inoa...@hotmail.com> wrote:
>First in your response you wrote: "Assuming, for the moment,
>the sound pressure level claimed is measured at a conventional
>1 meter, 145 dB SPL tells us that the source is producing 2000
>ACOUSTIC WATTS, assuming half-space radiation."
>
>Well, assuming halv space radiation at 20 Hz in a room is
>stupid, would you not agree?
Not in most houses, it is not. While masonery walls might be the
norm in Sweden, in North America, however, the convention is
stick-framed sheathed in drywall, and these walls are QUITE
transparent at 20 Hz.
> All rooms I have experiensed have seartainly had both floor
>and backwall. Actually, they've had sidewalls to! So your
>assumption is about 18 dB off! (64 times.)
That's only under the rather dubious assumption that then
reflection coefficient of all surfaces is 100%. In practice, it
is substantially less, reducing your room gain considerable at
low frequencies.
> Apart from that, I have never claimed 145 dB, but 139 dB,
>which is another 6 dB (4 times power ratio which make 256 times
>togather) down fron 145 dB. So the actual acoustic output is in
>fact not 2000 watts as you say, but 256 times lower. i.e approxi-
>matly 80 W.
Sir, you are heaping epicycles upon epicycles.
>When it comes to pumping capacity, it is not easy to determine
>an exact value necesarry to produce 139 dB, since it depends so
>much on the loading, but I think we can agree on something right
>under 80 liters p-p at 20 Hz in a room with supporting walls but
>which is non sealed. Right?
And that precisely contradicts your claims above. First you
claim the gain is 18 dB, no you claim it is not. Which is it?
> At higher frequenses, smaller strokes are needed. In a non
>reactive loading, the proportionality is (1/frequency)^2. So if
>80 liters is needed at 20 Hz, only 20 liters is needed at 40 Hz.
>and at 80 Hz, the necesarry pumpcapacity is 5 liters. Still text-
>book knowleadge, so I hope you agree so far.
> If Profundus Z-4 were a closed system, a stroke of around
>12" would be needed, You are right, but it is not! I can not
>see the reason why you speculate again? Profundus Z-4 is not a
>closed system but a tuned system!
All systems are tuned, sir. WHat you mean here, I would presume,
is that it is a fourth order vented system instead of a second
order closed system. If you insist on trying to teach me a
lesson in accoustics and speakers, it would serve you well to
get the terminology and the basic facts straight.
> In fact the measured stroke of the ports at full power 20 Hz
>is close to one metre, 12" is far from enough since the port
>area is significantly smaller than the membrane area.
WHat on earth do you mean by "the stroke of the ports?"
>Conclusion
>If you have further questions in the future mr Pierce, about Ino
>Audios Profundus Z-4 system, please email me directly instead
>of making a fool of yourself again (inoa...@hotmail.com).
Oh, you mean like making a fool by first claiming a room gain of
18 dB then claiming it's not? Or how about declaring that a
second0order mechanical resonant system is not tuned?
> Or make a fool of yourself if you like! I do not care. But I
>will not respond to any further low level criticism based on
>false assumptons.
First, sir, I might suggest you lower your tone. Second, I would
STRNGLY suggest that if you are looking for a whipping boy, you
might consider the person who rather blatantly misrepresented
your views on this newsgroup. I did not make these numbers up:
they were presented by him. Third, YOUR assertions are based on
an entire set of dubious assumptions themselves, at least one
set of which you succeed in conatrdicting yourself on.
> If you want to say something, first get the
>facts straight!
Indeed, excellent advise. For example, are you aware of the FACT
that a sealed box system is NOT, as you claim "untuned," unless
you are assertion there is no mass or compliance reactance in
the system? Are you aware of the FACT that your claim of 18 dB
room gain is based on the assumption that the reflection
coefficients of the surfaces are 100% at 20 Hz?
Are you ALSO aware of the FACT that the figures that were being
discussed were NOT made up by me, but the result of a series of
misquotes by your friend who chose to misrepresent them? WHy not
chastise him?
Ingvar G. Oehman
> >Well, assuming halv space radiation at 20 Hz in a room is
> >stupid, would you not agree?
>
> Not in most houses, it is not. While masonery walls might be the
> norm in Sweden, in North America, however, the convention is
> stick-framed sheathed in drywall, and these walls are QUITE
> transparent at 20 Hz.
*Right you are, sir! I am well aware of the differenses in wall-
quality over the world, but remember that this is a system for
recording studios - though a place were damping at low frequences
is purpously put in, damping at extreme lows are quite small
(specially from the walls adjacent to the speakers). A fact diffi-
cult to go around at long wavelengths when no leakage to adjacent
rooms is allowed.
I have installed no Profundus Z-4 systems in Kina where walls
are made of paper. :-) Neither did I refer so such installations
when specifying the output capacity of the system.
Also, tree walls was just a simplifyed example, not to radical
I hoped, to get us to agree on. I was wrong. Obiously you rather
believe that the same pressure can be measured indors as when the
loudspeaker is placed on a parking lot (with only the tarmac to
support it = true halfspace as you suggested). I think you are
wrong. Very, very much wrong. Please do the experiment! I have
done it many times. Aktually, it is not uncommon to register room
gains of far more than 18 dB down at 20 Hz, since walls are ref-
lected in each other.
Please remember that the stated 139 dB is not just a theoretical
calculation, it is also a measured value.
I do not see any conflict between theory and practice here.
Well, assuming that a proper theory is used, i.e. one that do
suggest a much, much higher level than you have indicated.
> > All rooms I have experiensed have seartainly had both floor
> >and backwall. Actually, they've had sidewalls to! So your
> >assumption is about 18 dB off! (64 times.)
>
> That's only under the rather dubious assumption that then
> reflection coefficient of all surfaces is 100%. In practice, it
> is substantially less, reducing your room gain considerable at
> low frequencies.
*Well, sure 100% is a bit optimistic, I give you that, I did
a simplification and hoped to get away with it :-).
But in practice, it does not matter since room gain in a real
life room is not made up by only three walls. At frequences
down at 20 Hz (well below standing waves in the rooms used)
the pressure can not eskape and a room gain of much more than
18 dB is most often the case, at least in a closed compartment,
like the control room of a recording studio. Actually, in a
slightly larger room even higher room gain is to expect since
we then have the room nodes also, though beeing quite depending
on where the listening place is in the room. I hope I am using
the right words here.
> > Apart from that, I have never claimed 145 dB, but 139 dB,
> >which is another 6 dB (4 times power ratio which make 256 times
> >togather) down fron 145 dB. So the actual acoustic output is in
> >fact not 2000 watts as you say, but 256 times lower. i.e approxi-
> >matly 80 W.
>
> Sir, you are heaping epicycles upon epicycles.
*I am? Well think about this: You claim 2000 W acoustic power. This
is due to a combination of two things; you assume 145 instead of
139 dB, and you also ignore the main part of the room support.
Heaping the two is here the acurate thing to do. I do not blame
you for the 6 dB between 139 and 145. It was due to flawed
information given to you, but since you used it for yours 2000 W
calculation, we have to deduct it to reach the true output level.
I am sure you agree if you think about it.
Compare theory with actual measurement if you do not believe it.
Actually, if room valls are ignored, the difference between 17
Hz and 20 Hz is very importante also. In a free field or half field,
going from 17 to 20 Hz reduces the nessesary pumping capacity with
a factor of 0,7225. In a fairly closed room however, 17 or 20 Hz
does not amount to much difference in needed pumping capacity.
> >When it comes to pumping capacity, it is not easy to determine
> >an exact value necesarry to produce 139 dB, since it depends so
> >much on the loading (stiffness of walls, size of the room), but
> >I think we can agree on something under 80 liters p-p at 20 Hz
> >in a room with supporting walls but which is non sealed. Right?
> And that precisely contradicts your claims above. First you
> claim the gain is 18 dB, no you claim it is not. Which is it?
*Que? The gain is about 18 dB (or more) and thus "only" less than
80 liters p-p is needed.
Actually, the full 18 dB (or more) gain is not always reached
at 1 metre, due to geometric reasons (at short distanses, reflex-
ions are proportionally further away from the measurement
microphone than primary source sound). If not correctly understood,
this can give a false impression of absorbtion from the walls
being present (I do not say you have done such mistakes, I am just
pointing out the risk).
To get a true figure regarding wall absorbtion, one must
measure at longer distance, but of coarce that introduces a new
difficulty - to separate gain from early reflexions and cavity-
gain from the room (which can be considered an effekt from many,
many reflexions)!
Who said room room acoustics was easy?! :-)
Anyway, at longer distance, say 3 metres (which theoretically
cost a 9,5 dB of pressure loss if the soundwaves are radiated in
a linearly expanding manner. like 4pi, 2pi pi or pi/2) the room
gain is typically higher than 18 dB, so in most cases, far more
than 129,5 dB (139 - 9,5 = 129,5 dB) is reached at specified max
power, i.e. at 80 litres p-p.
So our 139 dB at one meter spec, is in fact moderate and does
not need the full 18 dB room gain to be reached.
> > At higher frequenses, smaller strokes are needed. In a non
> >reactive loading, the proportionality is (1/frequency)^2. So if
> >80 liters is needed at 20 Hz, only 20 liters is needed at 40 Hz.
> >and at 80 Hz, the necesarry pumpcapacity is 5 liters. Still text-
> >book knowleadge, so I hope you agree so far.
> > If Profundus Z-4 were a closed system, a stroke of around
> >12" would be needed, You are right, but it is not! I can not
> >see the reason why you speculate again? Profundus Z-4 is not a
> >closed system but a tuned system!
>
> All systems are tuned, sir. WHat you mean here, I would presume,
> is that it is a fourth order vented system instead of a second
> order closed system. If you insist on trying to teach me a
> lesson in accoustics and speakers, it would serve you well to
> get the terminology and the basic facts straight.
*Well, you are right. I would prefere if this discussion were in
swedish! Sorry for my mistake. I shall try my best to use a more
adequat terminology.
The answer to your question, nay presumption, (I se no question-
mark :-) is that the system is made in such a manner so that many
would consider it to be a "forth order system". In real life
however, due to the system design (internal losses and acoustic
distanses) it behaves closer to a third order system than is normal
for a bass reflex system, thus falling only a little bit more than
18 dB per octave in free field and a little more than 6 dB per
octave in a control room sized closed room. However, the maximum
pressure capacity at frequences below 20 Hz falls rather rapidly.
Mechanical efficiency (system pump/drivers pump)is less than 1:1
below 14 Hz.
> > In fact the measured stroke of the ports at full power 20 Hz
> >is close to one metre, 12" is far from enough since the port
> >area is significantly smaller than the membrane area.
>
> WHat on earth do you mean by "the stroke of the ports?"
This is a joke, right? You do know how a ported system works?
There is air in the port. Driven by the pressure variations in
the box caused by the driver, the air in the port moves forth
an backwards. Due to the resonanse between the air spring of
the enclosed air inside the box and the mass of the air in the
port, the volume speed of the port exceeds that of the driver
if losses are low enough and exitation is in the right frequency
range. This air movement in the port can be measured. And if you
multiply the movement by the port area you get the pump volyme,
not very complicated.
Except for the non infinite compliance of a slave membrane
(a passive radiator), a port behaves kind of like a slave
membrane - but without the actual membrane. :-)
> >Conclusion
> >If you have further questions in the future mr Pierce, about Ino
> >Audios Profundus Z-4 system, please email me directly instead
> >of making a fool of yourself again (inoa...@hotmail.com).
>
> Oh, you mean like making a fool by first claiming a room gain
> of 18 dB then claiming it's not? Or how about declaring that
> a second0order mechanical resonant system is not tuned?
No, I did not mean that kind of a fool. :-)
> > Or make a fool of yourself if you like! I do not care. But I
> >will not respond to any further low level criticism based on
> >false assumptons.
>
> First, sir, I might suggest you lower your tone. Second, I would
> STRNGLY suggest that if you are looking for a whipping boy, you
> might consider the person who rather blatantly misrepresented
> your views on this newsgroup. I did not make these numbers up:
> they were presented by him.
Well, he made some mistakes, but only due to lack of correct
information. Also, though giving me an impression of being very
intelligent, I do not think he is educated in acoustics. So he
did his best. I respect that, no one can ask for more. And he
did seartainly not aim at whipping someone, as you did.
And, when he got the reactions from you, he immediatly
contacted me to get accurate information. I did appriciate that.
I then also suggested to him, to ask you to do the same thing -
contact me if questions remained.
You did not. Nor did you try to find out anyting. You
prefered to argue against inkorrect assumptions made up by
yourself!
Please understand that I have no doubt your knowleadge is
great, but the way you have argued this case have lacked the
component I find most essential for reaching a desent quality
in a disussion - a joint search for the facts.
I know our speaker systems. You do not, nor du you try to
find out about them by asking. Instead you argue against facts
you made up yourself. Why? Not very creative.
Or rather - very creative! :-)
If you are interrested in the how's and why's of our systems,
sir, feel free to ask!
I am sure we can agree on everything. Neither you or me are
likely to throw the laws of nature. But until you know every-
thing about our loudspeaker systems, do not tell me how they
work!!!
> Third, YOUR assertions are based on an entire set of dubious
> assumptions themselves, at least one set of which you succeed
> in conatrdicting yourself on.
No, no, no. My assertions are based on real life measurements!
And; the results from these does in no way contradict the theories.
Actually, in most cases a lot higher pressures than the stated
139 dB are achievable, both in theory and in practice. Especially
when recalculated for longer distanses.
So if your "theories", combined with your assumptions, predicts
something very different, they are simply wrong! A theory that can
not be used to predict real life is not a theory at all, at best
it is a hypothesis. A non valid one.
> > If you want to say something, first get the
> > facts straight!
>
> Indeed, excellent advise. For example, are you aware of the FACT
> that a sealed box system is NOT, as you claim "untuned," unless
> you are assertion there is no mass or compliance reactance in
> the system?
Well, again: Sorry! I shall try to avoid calling a ported system
a "tuned system" (to avoid this rediculous semantic argument you
are persuing, again and again).
Perhaps "tuned BOX" would be more appropriate and to your
liking? I mean; the closed box resonance is a combinatory effect
with the woofer. It does rather modify the driver resonance than
being a resonance of its own. And strictly technical; it (driver
in the box) can be given a Qt of below 0,5. Right?
Can an aperiodic system be called "tuned"? Just kidding. :-)
Anyway, I can promise you one thing; I shall seartainly avoid
ever calling a closed box an "untuned" system! So far I believe
I have managed that. Actually, I have probably only done it in
your imagination.
I do like this idea though: Calling a PORTED system "untuned",
until the port have been given it's proper dimensions! That
would be semantically correct, would it not? :-)
> Are you aware of the FACT that your claim of 18 dB room gain
> is based on the assumption that the reflection coefficients
> of the surfaces are 100% at 20 Hz?
Of coarce I am! And it is a practical and a close enough approxi-
mation to a control room of a recording studio. The reflexion
coefficients inability to reach all the way to 100% at 20 Hz
is well compensated for by later multiple reflexions from all
other walls. Measurements speak for themselves, so it is not
really an "assumtion" at all, is it? It is facts well verified.
> Are you ALSO aware of the FACT that the figures that were
> being discussed were NOT made up by me, but the result of a
> series of misquotes by your friend who chose to misrepresent
> them?
Yes, but I believe that the correction of the figures was
made before I entered this discussion. Right? I'm not
absolutly sure since I have read only fragments of what has
been said.
> WHy not chastise him?
Why would I do that? I do not want to chastise anyone.
Quite surprized by your initial aggressive approach, I
only vanted to explain the workings of our systems, and
thus the reasons to our specifications.
I expected a respons from you more like. "Okej, thank you
for clarifying everything!". Your respons was nothing like
that.
Anyway, I hope everything is clear now, and thank you sir,
for putting me up to the task!
I hope we can meet under less stressful conditions than
this "verbal competition with public". Personally I do not
mind the public, but I can see that it does induce quite a
lot of prestige, blocking the best path to find out "how
things really were".
And again: You are very welcome to email me directly if
any questions remain. (inoa...@hotmail.com)
Best regards, Ingvar G. Öhman, Ino Audio
Thomas A
> Are you ALSO aware of the FACT that the figures that were being
> discussed were NOT made up by me, but the result of a series of
> misquotes by your friend who chose to misrepresent them? WHy not
> chastise him?
Dear Mr. Pierce,
first I want to apologize to you and to Ingvar Oehman for the two
misquoutes made by me. The initial misquote, "145 dB at 1 metre" was
actually written in the original text from Ino Audio product guide,
and thus not a serious misquote in my opinion. You may disagree,
that's ok, although you stated that the difference between 139 dB and
145 dB is minor when the claims are "a factor of 1000 wrong". The
second misquote, or translation error, came in the last sentence of
the extended quotation AFTER you gave these numbers, which should read
"Max sound pressure is in normal cases 139 dB at one metre from the
speakers in all normal rooms since the impact of DISTANT WALLS in the
room at such small distances are small". This is the "series of
misquoutes" that would be relevant for your statemet above. I don't
agree upon that this a series of misquotes relevant for the central
question, i.e. the issue of whether it is possible to generate 139 dB
at just below 20 Hz in a room, which you clearly state several times
is against the laws of physics.
Looking at the order of the posts in the thread, your calculations
came after one statement only, which was "145 dB at one metre @ 17
Hz", with no information about the room, driver specification, or
vented/closed system. From this info only, you gave all these numbers
of excursion limits and acoustical power. These did not come from me.
The room which I did not specify at that point, could equally have had
a room size similar to a car, in which it's known that very high SPL
can be generated. Secondly, you also made one calculation with the
assumption that the excursion limit was 1.5 cm, which in the given
case was 5 cm. Third, among other "claims" that you commented upon a
statement which contained the word "servo-control", in which I did not
see any "claim" whatsoever that "servo-control" would be relevant for
the comparison of the amount of air being pumped by the Z-4 system.
Fourth, you also stated that the difference between 145 and 139 dB is
minor compared to the fact that they are making claims of 30-40 dB
higher than seems even feasible. In addition you give values of
maximial 118 dB in another post, without any giving any complete
information as to what circumstances and environmental factors you
have chosen for the calculation. Finally, there is no comment upon the
previous calculation from Ino Audio.
I will now rest my case here, before this thread gets too infected. My
wish is that you would do a in-room calculation, with all room
parameters and with the data at hand to either show that the claim,
during the cirumstances, would be correct (i.e. 139 dB) or wrong as
you previously showed (i.e. 118 dB). For a reader not having the
knowledge of acoustics, it is impossible to make a conclusion from
this thread.
Best regards,
Thomas